feat: Orthogonal (elbow) arrows for diagramming (#8299)

Co-authored-by: dwelle <5153846+dwelle@users.noreply.github.com>

packages/excalidraw/data/transform.test.ts

@@ -771,6 +771,7 @@ describe("Test Transform", () => {
       const [arrow, rect] = excalidrawElements;
       expect((arrow as ExcalidrawArrowElement).endBinding).toStrictEqual({
         elementId: "rect-1",
+        fixedPoint: null,
         focus: 0,
         gap: 205,
       });